Starting with erroneous data such as these, what can be expected as the result of an expe rimental injection of the liver made by Cru veilhier, those who are thoroughly informed upon the exact anatomy of this organ will have no difficulty in anticipating; but to those who are only imperfectly acquainted with it, his con clusions must appear startling :—" Le foie ainsi injecte soumis a divers agens chimiques a pre sente les resultats suivans : 1, l'injection bleue, c'est-a-dire celle de la veine cave, avait pen& tre dans la partie centrale des grains glandu leux, partie qu'on appelle substance jaune du foie. Au milieu de la partie centrale etait l'injection jaune, c'est-a-dire l'injection du canal biliare. Autour de l'injection bleue, etait l'injection rouge, c'est-a-dire, l'injection de la veine porte, et de l'artere hepatique, qui occupait toute la substance dite rouge du foie. 11 suit de a que chaque grain glanduleux presente un appareil vasculaire ainsi dispose: 1, au centre, un canal biliare ; 2, sue un plan plus excentrique, nn cercle vas culaire forme par les ramifications de la veine hepatique ; 3, un cercle vasculaire concen trique au precedent, forme par les ramifications de la veine porte et de l'artere hepatique." Thus in the centre of his lobule, Cruveilhier'* found the yellow colour of the ducts, most probably effused and colouring the whole of the yellow portion of his lobule. Next came a circle of blue, and then a circle of red, formed conjointly by the portal vein and hepatic ar tery. Now we have shewn that the centre of Cruveilhier's lobule is an uncongested patch formed by the contiguous margins of several adjoining hepatic lobules, and having an inter lobular space for a centre ;—where, therefore, could we expect to find the yellow but in the interlobular space, and diffused immediately around it, so that the colouring matter would obscure the red injection of the portal vein and artery of that immediate point. Around the uncongested patch and in the congested sub stance we should find the intralobular veins of three or four or five surrounding hepatic lo bules, (hence the variable size of Cruveilhier's lobules,) embracing by a kind of zone the yellow centre ; and externally to the vein, the surrounding interlobular fissures would display the red injection of the portal vein and hepatic artery.
4. Disorders of biliary excretion.— Bil iary congestion may be produced by various causes; the most frequent is temporary thick ening of the mucous lining of the ducts from inflammation or capillary congestion ; this will simply diminish the calibre of the ducts or produce a complete stricture. The obstruction may endure for a shorter or longer period ; the swelling of the membrane may subside and the tube be restored to its original dimen sions, or it may become chronic and be a per manent impediment to the free current of the bile. Another cause of congestion of the bile ducts is hepatic venous congestion, which acts by producing pressure upon the lobular biliary plexus and interlobular ducts. This is usually a chronic cause. Congestion of the bile-ducts may likewise depend upon the impaction of a gall-stone in the larger biliary ducts or ductus choledochus, obliteration of one of the ducts by the pressure of a tumour, disease of the pancreas, or thickening of the mucous mem brane of the duodenum. In each of these cases the ducts are loaded with bile, which gives a yellowish or greenish hue to the whole substance of the liver. Biliary congestion in a chronic form is usually accompanied with more or less of hepatic venous congestion.
When one of the bile-ducts is obliterated or obstructed by a biliary concretion, the ducts become dilated above the constriction, and considerable reservoirs are formed in the sub stance of the organ. If the impediment exist in the ductus choledochus, the gall-bladder becomes greatly distended as well as the biliary ducts. The irritation caused by the pressure
of the bile has given rise to inflammation and ulceration of the coats of the gall-bladder or of the ducts, and the bile has been effused into the peritoneal cavity and produced death. When the cause of the obstruction is a biliary calculus of moderate size, the pressure of the column of the bile will sometimes force it on wards into the duodenum, and thus remove the impediment. In other cases, when the obstruction occurs in the cystic duct, the bile ceases to enter the gall-bladder, the sac be comes thickened and diminished in size, and filled with a colourless viscid mucus.
5. Diseases of the parenchyma.— The diseases of the substance or parenchyma of the liver may be referred to the following a, inflammation ; b, hypertrophy ; c, atrophy ; d, softening ; e, induration ; j; fatty degene ration; g, pus ; h, tubercle ; scirrh us ; k, med larysarcoma ; 1, fungus hwmatodes; melanosis.
a. Itylammation.—The tissue of the liver is liable to inflammation,—hepatitis,orthe lobular hepatitis of some writers. fhe symptoms, like those detailed in the consideration of inflam mation of the serous membrane, are severe and prominent, and clearly indicative of the nature of the disease. The pathologic appearances are deep redness, softness, general congestion, and enlargement of the organ from distension with blood. This condition is but rarely ob served, from the circumstance of inflamma tion of the liver having no direct tendency to cause death, but being rather the precursor of the various other forms of disease which affect the organ. All the changes which occur in the liver are preceded or accompanied by in flammation acute or chronic, but more fre quell fly by the latter, and in most instances by de rangement of the venous circulation, and, occa sionally, of the biliary excretion, giving rise to a complication of venous and biliary congestion.
h. Hypertrophy of the liver is increase of bulk of the organ, not depending, as in con gestion, upon the quantity of blood circulating through it, but upon actual augmentation of the tissues of which it is composed. This state of enlargement of the liver may be gene ral, or it may be confined to a part, as to a single lobe. Its predisposing cause is proba bly irritation of the mucous membrane of the ducts which gives rise in the first instance to retarded circulation and venous congestion, or it may be impediment either in the circulation through the heart, or through the rest of the venous system ; or, again, it may depend upon diminution of the general powers of the system, as in a scrofulous constitution. The lobules are always in a state of partial congestion, re sembling the second stage of hepatic venous congestion ; the congested portion presents a deep red tint, and the uncongested part is ramose or convoluted in appearance, of a dirty white, greyish, yellowish, or greenish hue, in proportion to the condition of the biliary ap paratus and to the quantity of bile contained within the liver. Sometimes the organ is pale, and appears deficient in its supply of blood; at other times it has a generally diffused red ness, or the congestion may be greater in some situations than in others. The consistence of the liver in hypertrophy is equally variable with its colour : sometimes it is softer than natural, at other times it is dense and appa rently granulated, the uncongested part pro jecting from the surface, and the congested portion sinking beneath its level. Ilyper trophy of the liver is generally associated with chronic disease of the lungs, scrofula, and rickets, and often exists as a cause in ascites. It has been observed fifteen, eighteen, thirty-five, and even forty pounds in weight, and to have produced the displacement of the other abdo minal viscera by its enormous size.